centos 6
race weakness #27

5

Weakness Breakdown


Definition:

A race condition exists when parallel code accesses shared data without proper coordination. An attack that uses a race-condition weakness takes advantage of the unsafe data access to manipulate how one of the parallel sections of code reacts. Even though each process runs as intended, the outcome is unexpected. For example, consider a bank service that depends on an encryption key that it reads from a known location. An independent cryptography service is responsible for generating the key and placing it where the bank is expected to read it in a timely manner. If the bank and cryptography services do not coordinate with each other, then the bank may read a blank encryption key before cryptography writes the key to the location. This can effectively turn off all encryption for the bank without either service, or the administrator, knowing that something has gone wrong.

Warning code(s):

This accepts filename arguments; if an attacker can move those files, a race condition results..

File Name:

tar-1.23/gnu/fchmodat.c

Context:

The highlighted line of code below is the trigger point of this particular Centos 6 race weakness.

 #ifndef HAVE_LCHMOD
/* Use a different name, to avoid conflicting with any
   system-supplied declaration.  */
# undef lchmod
# define lchmod lchmod_rpl
static int
lchmod (char const *f _GL_UNUSED, mode_t m _GL_UNUSED)
{
  errno = ENOSYS;
  return -1;
}
#endif

/* Solaris 10 has no function like this.
   Invoke chmod or lchmod on file, FILE, using mode MODE, in the directory
   open on descriptor FD.  If possible, do it without changing the
   working directory.  Otherwise, resort to using save_cwd/fchdir,
   then (chmod|lchmod)/restore_cwd.  If either the save_cwd or the
   restore_cwd fails, then give a diagnostic and exit nonzero.
   Note that an attempt to use a FLAG value of AT_SYMLINK_NOFOLLOW
   on a system without lchmod support causes this function to fail.  */

#define AT_FUNC_NAME fchmodat
#define AT_FUNC_F1 lchmod
#define AT_FUNC_F2 chmod
#define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW
#define AT_FUNC_POST_FILE_PARAM_DECLS , mode_t mode, int flag
#define AT_FUNC_POST_FILE_ARGS        , mode
#include "at-func.c" 

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